Hydrazino nickel thio-bis-phenolates and polyolefins stabilized thereby against the effects of heat and light

ABSTRACT

The disclosure relates to a new class of compounds useful in stabilizing organic materials against the effects of heat and light, such materials especially including polymers such as polyolefins. The new compounds are hydrazine complexes of nickel thio-bis-phenolates, where the thio-bis-phenol is of the formula.   WHERE R is selected from the group consisting of hydrogen, normal alkyl or normal alkenyl, and R1 is selected from the group consisting of a normal, secondary, tertiary or cyclic alkyl group. The hydrazines used in making the complexes are of the formula   where R2, R3 and R4 are independently chosen from the group hydrogen and primary, seconary and tertiary alkyl groups consisting of 1 to 8 carbon atoms, and R3 and R4 may be joined together to form a heterocyclic structure. The resulting nickel complexes have been found to function as superior stabilizers for organic polymers and for polyolefins in particular, and also to perform synergistically in combination with other stabilizers of the prior art.

United States Patent [191 J ancis [54] HYDRAZINO NICKEL THIO-BlS-PHENOLATES AND POLYOLEFINS STABILIZED THEREIY AGAINST THE EFFECTS OF HEAT AND LIGHT [75] Inventor: Ehur Harry Jancis, Naugatuck,

Conn.

[73] Assignee: Uniroyal, Inc, New York, NY.

[22] Filed: Feb. 6, 1974 [21] Appl. No.: 439,801

[52] US. Cl "260/4575 N; 260/4585 S; 260/4595 F; 260/458 NT; 260/439 [51] Int. Cl. COQG 6/00 [58] Field of Search... 260/4575 N, 439 R, 45.85 S, 260/458 NT, 45.95 F

[56] References Cited UNITED STATES PATENTS 3,215,717 11/1965 Foster 260/4575 3,282,887 11/1966 Soeder 260/4575 3,632,825 1/1972 Jordan 260/439 3,636,022 1/1972 Bright 260/4575 Primary Examiner-V. P. Hoke Attorney, Agent, or FirmBruce F. Jacobs, Esq.

[57] ABSTRACT The disclosure relates to a new class of compounds useful in stabilizing organic materials against the effects of heat and light, such materials especially in- [4 1 Dec. 9, 1975 eluding polymers such as polyolefins. The new compounds are hydrazine complexes of nickel thio-bisphenolates, where the thio-bis-phenol is of the forary, tertiary or cyclic alkyl group. The hydrazines used in making the complexes are of the fonnula where R R and R are independently chosen from the group hydrogen and primary, seconary and tertiary alkyl groups consisting of 1 to 8 carbon atoms, and R, and R may be joined together to form a heterocyclic structure.

The resulting nickel complexes have been found to function as superior stabilizers for organic polymers and for polyolefins in particular, and also to perform synergistically in combination with other stabilizers of the prior art.

20 Claims, N0 Drawings HYDRAZINO NICKEL THIO-BIS-PHENOLATES AND POLYOLEFINS STABILIZED THEREBY AGAINST THE EFFECTS OF HEAT AND LIGHT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a novel class of compounds useful in stabilizing organic materials against the effects of heat and light. The materials to be protected by these compounds include organic polymers such as polyolefins and more particularly, polyethylene and polypropylene, and the invention includes compositions containing such polymers and said stabilizers incorporated therein.

2. Description of the Prior Art Metal salts of thio-bis-phenols have been known as rubber antioxidants for a long time (U.S. Pat. No. 2,310,449 1943). in particular, nickel salts have been found to be very effective (U.S. Pat. No. 2,380,299 1945 These salts have also been found useful as lubricating oil additives (U.S. Pat. No. 2,402,448 1946). Nickel salts of para-alkylphenol sulfides have furthermore found use in polypropylene (U.S. Pat. No. 2,971,940 1961), polyethylene (U.S. Pat. No. 2,971,941 1961) as well as in other polyolefins (U.S. Pat. No. 3,006,886 1961). Because of the ease of its preparation (U.S. Pat. No. 2,971,968 1961; U.S. Pat. No. 3,390,160 1968) the para-tetramethylbutylphenol sulfide nickel salt has become the article of commerce. One of its advantages is that it is compatible with other additives that are commonly used in stabilizing polyolefins such as phenolics, thiodipropionates, phosphites, benzophenones and benzotriazoles (U.S. Pat. No. 3,006,885; 3,006,886; 3,074,910; 3,167,526; 3,481,897; 3,637,588).

Recently the butylamine complex of the nickel 2,2- thio-bis(4-tetramethylbutylphenolate) has made great inroads on the market of the above named predecessor, mainly because of its increased activity (U.S. Pat. No. 3,215,717 1965). This compound too is compatible with the usual compounding ingredients used in polyolefins (U.S. Pat. No. 3,218,294; 3,379,680; 3,481,897).

Most recently the alkanolamine complexes of nickel 2,2'-thio-bis(4-alkylphenolates) have been patented (U.S. Pat. No. 3,636,023 1972).

SUMMARY OF THE INVENTION In accordance with this invention it has been discovered that a new class of compounds composed of hydrazine complexes of nickel 2,2'-thio-bis(4-alkylphenols), or nickel 2,2-thio-bis(4,6-dialkylphenols), have superior activity as stabilizers against the effects of heat and light when incorporated in organic materials. These compounds are especially useful as additives to organic polymers especially polyolefins such as polyethylene and polypropylene.

An object of the present invention therefore is to provide a new class of compounds as well as specific members thereof especially useful as stabilizers of organic materials against heat and light.

A further object of the present invention is to provide a polymeric composition comprising a polyolefm stabilized against light and heat by the incorporation therewith of a compound of the present invention.

An additional object of the present invention is to provide a stabilizer which will function synergistically in combination with other stabilizers resulting in enhanced stability of polyolefins against heat and light.

PREFERRED EMBODlMENTS OF THE PRESENT INVENTION The thio-bis-phenols mentioned have the formula OH OH R ,S g R where R is hydrogen, n-alkyl or n-alkenyl. R is an alkyl group of any description. it can be normal, secondary, tertiary, cyclic and may contain unsaturation.

The preparation of thio-bis-phenols is fully described in the literature (prior art cited), more particularly, U.S. Pat. Nos. 2,971,940; 2,971,968 and 3,006,886.

R is usually hydrogen or methyl and R, a methyl, tertiary butyl or tertiary octyl group.

Representative 2,2'-thio bis-phenols include 2,2'-thio-bis-(4-ethylphenol) 2 ,2 '-thio-bis-(4-tert-butylphenol) 2,2'-thio-bis(4-tert-amylphenol) 2,2'-thio-bis-(4'-iso-propylphenol) 2,2-thio-bis-(4'-tert-octylphenol) 2,2-thio-bis-(4'-nonylphenol) 2,2-thio-bis-(4'-dodecylphenol) 2,2-thio-bis-(4-tert-butyl-ocresol) 2 ,2 '-thio-bis-(4'-tert-octyl-o-cresol) 2,2'-thio-bis-(4'-tert-octyl-6-allylphenol) 2,2-thio-bis-(4'-tert-octyl-6-npropylphenol) The hydrazines used in making the complexes have the formula where R R and R are independently chosen from the group consisting of hydrogen and primary, secondary and tertiary alkyl groups consisting of l to 8 carbon atoms and R and R may be joined together with the nitrogen to form a heterocyclic structure of the formula where x is 1 to 3, y is 1 to 3 and n is zero or 1. Examples of hydrazines having this heterocyclic structure are N- aminopyrrolidine, N-aminopiperidine and N-aminomorpholine.

The hydrazines used to complex the nickel thioisphenolates can be hydrazine itself, mono, dian trisubstituted hydrazines. The substituents are preferably alkyl groups. Two substituents could be joined together to form a cyclic structure. Thus N-aminomorpholine and N-aminopiperidine are very useful hydrazines for this invention.

Arylhyclrazines, heterocyclically substituted hydrazine and hydroxy ethyl hydrazines have been used to make the nickel complexes, but gave products inferior to simple alkylhydrazine complexes.

The hydrazines useful in preparing the nickel complexes of the invention are as follows:

hydrazine l ,1 -dimethylhydrazine l ,2-dimethylhydrazine 1,1,2-trimethylhydrazine 1 ,1-diethylhydrazine 1,2-diethylhydrazine 1, l -dimethyl-2-ethylhydrazine l ,l -dimethyl-2-n-propylhydrazine 1 ,l -dimethyl-2-isopropylhydrazine l ,1 -dimethyl-2-n-butylhydrazine l ,1 -dimethyl-2-sec-butylhydrazine l ,l -dimethyl-2-amylhydrazine l ,1 -di-n-propylhydrazine l ,l -di-isopropylhydrazine 1 ,1 -di-n-butylhydrazine l ,1 -di-sec-butylhydrazine 1-1di-amylhydrazine methylhydrazine ethylhydrazine iso-propylhydrazine n-propylhydrazine n-butylhydrazine sec-butylhydrazine n-amylhydrazine sec-amylhydrazine tert-amylhydrazine hexylhydrazine cyclopentylhydrazine cyclohexylhydrazine N-aminopyrrolidine N-amino-piperidine N-amino-morpholine, etc.

The hydrazines of choice are hydrazine itself and 1,1 dimethylhydrazine.

The use of hydrazines to complex the nickel thio-bisphenolates is the key to the invention. Ordinary amines have already been used to form analogous complexes. We found that compounds of this invention have superior activity to previously described compounds, e.g. in polypropylene fiber the dimethylhydrazine complex was superior to the corresponding butylamine complex (marketed as Cyasorb 1084).

The complexes of this invention are readily prepared by the methods described in the aforementioned prior art on amine complexes of nickel thio-bis-phenolates and as described in the examples below.

The compounds of this invention are useful for stabilizing organic materials against the effects of heat and light. They are particularly effective in stabilizing polya-olefins such as polyethylene and polypropylene. The nickel complexes obtained are compatible with all the other ingredients used to compound commercial resins such as phenolics, thioesters, lubricants, pigments and other light stabilizers. A synergistic effect is actually noted in using mixtures of hydrazino nickel compounds with benzotriazole or benzophenone type light stabilizers of the type commercially available.

The following specific Examples illustrate the practice of the invention.

EXAMPLE 1 Preparation of dimethylhydrazine nickel complex of 2,2-thio-bis-(p-tert-octylphenol)( l :1 salt) To a solution of 47 parts nickel 2(2-hydroxy-5'-tertoctylphenyl-thio)-4-tert-octylphenolate in 400 ml. chloroform was added 15 ml. 1,1-dimethylhydrazine followed by 15g. nickel acetate tetrahydrate in 200 ml.

water. After stirring 3 hours, the layers were separated. The chloroform layer was washed with water. The chloroform was filtered through cotton and was then evaporated. The green residue was triturated with hot ethanol whereupon the nickel salt crystallized. The salt was filtered and dried. The product melted at 260267C and contained 10.5% nickel by analysis Ni calculated 11.0).

Other hydrazine complexes were prepared in an analogous fashion. Hydrazine complex M.p. 255263C. Ni 10.3 Methylhydrazine complex M.p. 280300C. Ni 12.2 Dibutylhydrazine complex M.p. 238-245C. Ni 9.5 Aminomorpholine complex M.p. 245-265C. Ni

10.4 Phenylhydrazine complex M .p. l27150C. Ni 9.9 Aminopiperidine complex M.p. 260278C. Ni 1 1.5

EXAMPLE ll Nickel complex preparation from other thio-bis-phenols To 18g. of 2,2'-thio-bis(4-tert-butyl-o-cresol) in ml. chloroform was added 10 ml. 1,1-dimethylhydrazine followed by a solution of 15 g. nickel acetate tetrahydrate in 100 ml. water. The mixture was stirred 2 hours, another 5 ml. of 1,1-dimethylhydrazine was added, and stirred another hour. The layers was separated; the chloroform layer was washed with water and filtered through cotton. The residue after chloroform evaporation was recrystallized from methanol/water.

The product melted at 255-270C and contained 12.6% nickel.

In an analogous fashion were prepared the dimethylhydrazino nickel complexes from 2,2-thio-bis(4-tert-butylphenol) M.p. over 300C,

14.6% Ni 2,2'-thio-bis(4-nonylphenol) M.p. 202c.

2,2-thio-bis(6-allyl-4-tert-octylphenol) M.p.

l65-183C, 8.6% Ni 2 ,2'-thio-bis( 6-n-propyl-4-tert-0ctylphenol) M .p.

88l02C, 7.3% Ni EXAMPLE Hi This Example is designed to show the superiority of the material made in Example 1 to the commercial butylamine complex (Test A. below) Polypropylene fibers were drawn from Profax 6501 resin containing 0.2% distearyl thiodipropionate, 0.1% lrganox 1010 (a phenolic stabilizer), 0.05% dibutyl pcresol, 0.2% calcium stearate and 0.5% light stabilizer as follows:

A. 0.5% butylamine complex of nickel 2,2'-thiobis(4-tert-octylphenolate) B. 0.5% dimethylhydrazine complex (Example I) C. 0.25% 4-octyloxy-2-hydroxybenzophenone and 0.25% butylamine complex A D. 0.25% 4-octyloxy-2-hydroxybenzophenone and 0.25 dimethylhydrazine complex (Example I) E. 0.5% 4-octyloxy-2-hydroxybenzophenone F. 0.5% hydrazine complex (Example I) G. 0.25% hydrazine complex (Example 1) and 0.25%

4-octyloxy-2-hydroxybenzophenone H. No light stabilizer.

B, D, F and G are the Examples of the invention.

The multifilament yarn (ca. 300 denier) was mounted and exposed in a fluorescent Sunlight/Blacklight unit for 8 days. Tensile strengths and elongations were taken before and after aging.

% Initial properties retained Tensile Elongation A 66 21 B 79 37 C 79 38 D 97 M E 72 49 F 54 27 G 77 43 H 0 Note the synergistic effect with 4-octyloxy-2-hydroxybenzophenone in preserving the tensile strength.

EXAMPLE IV Days to Embrittlement OVEN FSLBL A. Hydrazine complex (Example I) 42 36 B Dimethylhydrazine complex 44 23 (Example I) C. Ethanolamine complex of nickel 36 I4 2 ,2'-thio-bis(4-tert-octylphenolate D. No nickel 23 i3 EXAMPLE V This Example is designed to show the general utility of hydrazino-nickel-bis phenolates in polypropylene.

Ten mil polypropylene films were compression molded from Profax 6501 resin containing 0.4 parts dilauryl thiodipropionate and 0.5 parts nickel stabilizer.

They were exposed in an oven at 300F and in a Fluorescent Sunlight Blacklight unit. The days to embrittlement were noted.

Days to Embrittlement Nickel complex OVEN FSLBL A. None 23 I3 B. Dimethylh drazine complex 3l 50 (Example C. Hydrazine complex (Example I) 35 50 D. Methylhydrazine complex (5x1) 35 49 E. Dibutylhydrazine complex(Ex.l) 46 37 F. Aminomorpholine com lex (ExJ) 4| 46 G. Aminopiperidine comp ex (Ex.l) 35 53 -continued Da s to Embrittlement Nickel complex OVEN FSLBL H. phenylhydrazine complex (Ex.l) 35 34 l. Dimethylhydrazino nickel complex of 2,2-thio-bis(4-tert- 26 42 butyl-ocresol) (Ex. II) J. Dimethylhydrazino nickel complex butyI-phenol) (Ex. II)

EXAMPLE Vl This Example is designed to show the usefulness of the compounds of this invention in polyethylene.

Ten (10) mil films were compression molded from Profax A60 008 polyethylene resin containing 0.05% distearyl thiodipropionate and 0.2 parts nickel stabilizer. They were exposed in a Fluorescent Sunlight Blacklight unit and the number of days to embrittlement noted.

Days to Embrittlement A. No nickel B. Dimethylhydrazine complex (Ex.l)

C. Hydrazine complex (Example I) 51 EXA M PLE Vll This Example illustrates the superiority of the compounds of this invention in polypropylene film.

Some films prepared in the same fashion as in Example IV were also exposed in a xenon arc Fadeometer. Results show hours to embrittlement.

Hours to Embrittlement No nickel salt 239 Butylamine complex of nickel 2,2'-thio-bis- 500 (4-tetramethylb utylphenolate) Hydrazine complex (Example I) 507 Dimethylhydrazine complex (Ex. I) 555 When compounded at the 0.1 part level with 0.l parts 4-octyloxy-2-hydroxybenzophenone the hours to embrittlement in the xenon arc Fadeometer are:

Hours to Embrittleme nt Butylamine complex (as above) 699 Hydrazine complex (Example I) 744 Dimethylhydrazine complex (Ex. I) I075 EXAMPLE Vlll This example illustrates the improved processing safety of the compounds of this invention in polypropylene over the commercial butylamine complex as measured by the melt index.

Dimethylhydrazine Melt Index Measurements of Extrudates Melt Index ASTM l238/T (Grams/l0 Minutes) Unextruded complex (Ex. I)

-continued Unextruded 450 475 500 25 Butylamine complex 5.0 5.8 7.2 7.2 8.7

(Example III A) The above Examples clearly illustrate the utility and effectiveness of the nickel complexes of the invention in preserving the physical characteristics of polyolefins against exposure to heat and light, either as the sole stabilizing agent or synergistically in combination with others. In Example lll, tests run against the nickel butylamine complex of the prior art show that all of the nickel hydrazine complexes except the hydrazine complex gave substantially higher preservation of tensile strength and elongation. The hydrazine complex while less effective with respect to tensile strength, gave a better elongation result. Significantly, the hydrazine complex with a hydroxybenzophenone stabilizer gave a clear picture of synergy.

In Example lV comparison with an ethanolamine complex of US. Pat. No. 3,636,023 in polypropylene film demonstrated clear superiority of the nickel hydrazine and dimethylhydrazine complexes of the invention.

The relative effectiveness of the nickel complexes of the invention are demonstrated in the oven and fluorescent blacklight sunlight tests of Example V.

As shown in Example Vl, the nickel complexes of the invention are highly effective when compounded with polyethylene.

[n Example VII comparison with the butylamine complex of nickel 2,2'-thio-bis(4-tetramethylbutylphenolate) demonstrated superiority of the nickel hydrazine and dimethylhydrazine complexes when compared alone and combined with 4-octyloxy-2-hydroxybenzophenone. Although some synergistic activity appears to exist with the butylamine complex combinations, it is obviously much greater in the combination with the nickel complexes of this invention.

In general, stabilizers of the present invention are effective over a broad range of concentrations, namely about 0.05% to about 5%. The specific proportion to be used will be within the skill of the worker in the art and will depend on the nature of the polymer, its intended use, and the conditions to which it will be exposed.

The stabilizers are incorporated in the polymeric material in a manner well known to the art as by intimately mixing with the polymer prior to extrusion by milling or suspension in the material to be shaped.

I claim:

1. A stabilized polyolefin composition having incorporated therein a stabilizing amount of a hydrazino nickel thio-bis-phenolate which is a hydrazine complex of a nickel thio-bis-phenolate, where the thio-bis phenol is of the formula:

OH OH R s R where R is selected from the group consisting of hydrogen, normal alkyl or normal alkenyl, and R is selected from the group consisting of normal, secondary, tertiary and cyclic alkyl groups, and the hydrazine is of the formula where R R and R are independently chosen from the group consisting of hydrogen and primary, secondary and tertiary alkyl groups consisting of l to 8 carbon atoms and R and R may be joined together with the nitrogen to form a heterocyclic structure of the formula 5. A stabilized polyolefin composition according to claim 1 wherein the polyolefin is polypropylene.

6. A polyolefin composition stabilized against the effects of heat and light, said composition having incorporated therein stabilizing amounts of heat and UV stabilizing materials together with a stabilizing amount of a hydrazino nickel thio-bis-phenolate which is a hydrazine complex of a nickel thio-bis-phenolate, where the thio-bis phenol is of the formula:

RHS

where R is selected from the group consisting of hydrogen, normal alkyl or normal alkenyl, and R, is selected from the group consisting of normal, secondary, tertiary and cyclic alkyl groups, and the hydrazine is of the formula:

where R,, R and R are independently chosen from the group consisting of hydrogen and primary, secondary, and tertiary alkyl groups consisting of l to 8 carbon atoms and R and R may be joined together with the nitrogen to form a heterocyclic structure of the formula where x is l to 3, y is l to 3 and n is zero or I.

7. A polyolefin composition according to claim 6 wherein the UV stabilizing material is a 2-hydroxy-4- alkoxy-benzophenone.

8. A polyolefin composition according to claim 6 wherein the UV stabilizing material is an o-hydroxyphenyl benzotriazole.

9. A polyolefin composition according to claim 6 wherein the heat stabilizing material is a thioester.

10. A polyolefin composition according to claim 6 wherein the UV stabilizing material is 4-octyloxy-2- hydroxy-benzophenone and the heat stabilizing material is dilauryl-thiodipropionate.

11. The method of of stabilizing polyolefin compositions against the effects of heat and light which comprises incorporating therein a stabilizing amount of a hydrazino nickel thio-bis-phenolate which is a hydrazine complex of a nickel thiobis-phenolate, where the thio-bis phenol is of the formula:

OH OH where R is selected from the group consisting of hydrogen, normal alkyl and normal alkenyl, and R is selected from the group consisting of normal, secondary, tertiary and cyclic alkyl groups, and the hydrazine is of the formula where R R and R are independently chosen from the group consisting of hydrogen and primary, secondary, and tertiary alkyl groups consisting of l to 8 carbon atoms and R and R may be joined together with the nitrogen to form a heterocyclic structure of the formula where x is l to 3, y is l to 3 and n is zero or l.

12. The method according to claim 11 wherein the compound incorporated is the dimethylhydrazine nickel complex of 2,2'-thio-bis(p-tert-octylphenol).

13. The method according to claim 11 wherein the compound incorporated is the hydrazine nickel complex of 2,2-thio-bis(p-tert-octylphenol).

14. The method according to claim 11 wherein the compound incorporated is the dimethylhydrazine nickel complex of 2,2'-thio-bis(4tert-butyl-o-cresol).

15. The method according to claim 11 wherein the compound incorporated is the dimethylhydrazine nickel complex of 2,2'-thio-bis(4-tert-butylphenol).

16. The method of stabilizing polyolefins against the effects of heat and light which comprises incorporating therein a stabilizing amount of a synergistic mixture of 4-octyloxy-2-hydroxybenzophenone and the dimethylhydrazine nickel complex of 2,2'-thio-bis(p-tert-octylphenol).

17. The method of stabilizing polyolefins against the effects of heat and light which comprises incorporating therein a stabilizing amount of a synergistic mixture of 4-octyloxy-2-hydroxybenzophenone and the hydrazine nickel complex of 2,2'-thio-bis(p-tert-octylphenol).

18. The method of stabilizing polyolefins against the effects of heat and light which comprises incorporating therein a stabilizing amount of a synergistic mixture of o-hydroxyphenyl benzotriazole and the hydrazine or dimethylhydrazine nickel complex of 2,2'-thio-bis(ptert-octylphenol).

19. The method of stabilizing polypropylene against the effects of heat and light which comprises incorporating therein a stabilizing amount of a thioester heat stabilizer, a stabilizing amount of 4-octyloxy-2hydroxybenzophenone UV stabilizing material together with a stabilizing amount of either the hydrazine or the dimethylhydrazine nickel complex of 2,2'-thio-bis(p-tertoctylphenol).

20. A stabilized polypropylene composition having incorporated therein a stabilizing amount of a thioester as a heat stabilizer, a stabilizing amount of 4-octyloxy- 2-hydroxy-benzophenone as a UV stabilizing material, and a stabilizing amount of a hydrazine or dimethylhydrazine nickel complex of 2,2'-thio-bis(p-tert-octylphenol).

l l t l 

1. A STABILIZED POLYOLEFIN COMPOSITION HAVING INCORPORATED THEREIN A STABILIZING AMOUNT OF A HYDRAZINO NICKEL THIO-BISPHENOLATE WHICH IS A HYDRAZINE COMPLEX OF A NICKEL THIO-BISPHENOLATE, WHERE THE THIO-BIS PHENOL IS OF THE FORMULA:
 2. A stabilized polyolefin composition according to claim 1 wherein the hydrazino nickel thio-bis-phenolate is the dimethylhydrazine nickel complex of 2,2''-thio-bis-(p-tert-octylphenol).
 3. A stabilized polyolefin composition according to claim 1 wherein the hydrazino nickel thio-bis-phenolate is the hydrazine nickel complex of 2,2''-thio-bis(p-tert-octylphenol).
 4. A stabilized polyolefin composition according to claim 1 wherein the polyolefin is polyethylene.
 5. A stabilized polyolefin composition according to claim 1 wherein the polyolefin is polypropylene.
 6. A polyolefin composition stabilized against the effects of heat and light, said composition having incorporated therein stabilizing amounts of heat and UV stabilizing materials together with a stabilizing amount of a hydrazino nickel thio-bis-phenolate which is a hydrazine complex of a nickel thio-bis-phenolate, where the thio-bis phenol is of the formula:
 7. A polyolefin composition according to claim 6 wherein the UV stabilizing material is a 2-hydroxy-4-alkoxy-benzophenone.
 8. A polyolefin composition according to claim 6 wherein the UV stabilizing material is an o-hydroxyphenyl benzotriazole.
 9. A polyolefin composition according to claim 6 wherein the heat stabilizing material is a thioester.
 10. A polyolefin composition according to claim 6 wherein the UV stabilizing material is 4-octyloxy-2-hydroxy-benzophenone and the heat stabilizing material is dilauryl-thiodipropionate.
 11. The method of of stabilizing polyolefin compositions against the effects of heat and light which comprises incorporating therein a stabilizing amount of a hydrazino nickel thio-bis-phenolate which is a hydrazine complex of a nickel thio-bis-phenolate, where the thio-bis phenol is of the formula:
 12. The method according to claim 11 wherein the compound incorporated is the dimethylhydrazine nickel complex of 2,2''-thio-bis(p-tert-octylphenol).
 13. The method according to claim 11 wherein the compound incorporated is the hydrazine nickel complex of 2,2''-thio-bis(p-tert-octylphenol).
 14. The method according to claim 11 wherein the compound incorporated is the dimethylhydrazine nickel complex of 2,2''-thio-bis(4-tert-butyl-o-cresol).
 15. The method according to claim 11 wherein the compound incorporated is the dimethylhydrazine nickel complex of 2,2''-thio-bis(4-tert-butylphenol).
 16. The method of stabilizing polyolefins against the effects of heat and light which comprises incorporating therein a stabilizing amount of a synergistic mixture of 4-octyloxy-2-hydroxybenzophenone and the dimethylhydrazine nickel complex of 2,2''-thio-bis(p-tert-octylphenol).
 17. The method of stabilizing polyolefins against the effects of heat and light which comprises incorporating therein a stabilizing amount of a synergistic mixture of 4-octyloxy-2-hydroxybenzophenone and the hydrazine nickel complex of 2,2''-thio-bis(p-tert-octylphenol).
 18. The method of stabilizing polyolefins against the effects of heat and light which comprises incorporating therein a stabilizing amount of a synergistic mixture of o-hydroxyphenyl benzotriazole and the hydrazine or dimethylhydrazine nickel complex of 2,2''-thio-bis(p-tert-octylphenol).
 19. The method of stabilizing polypropylene against the effects of heat and light which comprises incorporating therein a stabilizing amount of a thioester heat stabilizer, a stabilizing amount of 4-octyloxy-2-hydroxybenzophenone UV stabilizing material together with a stabilizing amount of either the hydrazine or the dimethylhydrazine nickel complex of 2,2''-thio-bis(p-tert-octylphenol).
 20. A stabilized polypropylene composition having incorporated therein a stabilizing amount of a thioester as a heat stabilizer, a stabilizing amount of 4-octyloxy-2-hydroxy-benzophenone as a UV stabilizing material, and a stabilizing amount of a hydrazine or dimethylhydrazine nickel complex of 2,2''-thio-bis(p-tert-octylphenol). 